The present invention relates to a vaccine formula allowing the vaccination of avian species, in particular chickens. It also relates to a corresponding method of vaccination.
Associations of vaccines against a number of viruses responsible for pathologies in chicken have already been proposed in the past.
The associations developed so far were prepared from inactivated vaccines or live vaccines. Their use poses problems of compatibility between valencies and of stability. It is indeed necessary to ensure both the compatibility between the different vaccine valencies, whether from the point of view of the different antigens used from the point of view of the formulations themselves. The problem of the conservation of such combined vaccines and also of their safety especially in the presence of an adjuvant also exists. These vaccines are in general quite expensive.
Patent applications WO-A-90 11092, WO-A-92 19183, WO-A-94 21797 and WO-A-95 20660 have made use of the recently developed technique of polynucleotide vaccines. It is known that these vaccines use a plasmid capable of expressing, in the host cells, the antigen inserted into the plasmid. All the routes of administration have been proposed (intraperitoneal, intravenous, intramuscular, transcutaneous, intradermal, mucosal and the like). Various vaccination means can also be used, such as DNA deposited at the surface of gold particles and projected so as to penetrate into the animal""s skin (Tang et al., Nature, 356, 152-154, 1992) and liquid jet injectors which make it possible to transfect at the same time the skin, the muscle, the fatty tissues and the mammary tissues (Furth et al., Analytical Biochemistry, 205, 365-368, 1992). (See also U.S. Pat. Nos. 5,846,946, 5,620,896, 5,643,578, 5,580,589, 5,589,466, 5,693,622, and 5,703,055; Science, 259:1745-49, 1993; Robinson et al., seminars in IMMUNOLOGY, 9:271-83, 1997; Luke et al., J. Infect. Dis. 175(1):91-97, 1997; Norman et al., Vaccine, 15(8):801-803, 1997; Bourne et al., The Journal of Infectious Disease, 173:800-7, 1996; and, note that generally a plasmid for a vaccine or immunological composition can comprise DNA encoding an antigen operatively linked to regulatory sequences which control expression or expression and secretion of the antigen from a host cell, e.g., a mammalian cell; for instance, from upstream to downstream, DNA for a promoter, DNA for a eukaryotic leader peptide for secretion, DNA for the antigen, and DNA encoding a terminator.).
The polynucleotide vaccines may also use both naked DNAs and DNAs formulated, for example, inside lipids or cationic liposomes.
The invention therefore proposes to provide a multivalent vaccine formula which makes it possible to ensure vaccination against a number of pathogenic avian viruses.
Another objective of the invention is to provide such a vaccine formula combining different valencies while exhibiting all the criteria required for mutual compatibility and stability of the valencies.
Another objective of the invention is to provide such a vaccine formula which makes it possible to combine different valencies in the same vehicle.
Another objective of the invention is to provide such a vaccine which is easy and inexpensive to use.
Yet another objective of the invention is to provide a method for vaccinating Gallinaceans which makes it possible to obtain protection, including multivalent protection, with a high level of efficiency and of long duration, as well as good safety and an absence of residues.
The subject of the present invention is therefore an avian vaccine formula comprising at least three polynucleotide vaccine valencies each comprising a plasmid integrating, so as to express it in vivo in the host cells, a gene with one avian pathogen valency, these valencies being selected from the group consisting of Marek""s disease virus (MDV), Newcastle""s disease virus (NDV) , infectious bursal disease virus (IBDV), infectious bronchitis virus (IBV), infectious anaemia virus (CAV), infectious laryngotracheitis virus (ILTV), encephalomyelitis virus (AEV or avian leukosis virus ALV), pneumovirosis virus, and avian plague virus, the plasmids comprising, for each valency, one or more of the genes selected from the group consisting of gB and gD for the Marek""s disease virus, HN and F for the Newcastle disease virus, VP2 for the infectious bursal disease virus, S, M and N for the infectious bronchitis virus, C+NS1 for the infectious anaemia virus, gB and gD for the infectious laryngotracheitis virus, env and gag/pro for the encephalomyelitis virus, F and G for the pneumovirosis virus and HA, N and NP for the avian plague virus.
Valency in the present invention is understood to mean at least one antigen providing protection against the virus for the pathogen considered, it being possible for the valency to contain, as subvalency, one or more natural or modified genes from one or more strains of the pathogen considered.
Pathogenic agent gene is understood to mean not only the complete gene but also the various nucleotide sequences, including fragments which retain the capacity to induce a protective response. The notion of a gene covers the nucleotide sequences equivalent to those described precisely in the examples, that is to say the sequences which are different but which encode the same protein. It also covers the nucleotide sequences of other strains of the pathogen considered, which provide cross-protection or a protection specific for a strain or for a strain group. It also covers the nucleotide sequences which have been modified in order to facilitate the in vivo expression by the host animal but encoding the same protein.
Preferably, the vaccine formula according to the invention comprises three valencies chosen from Marek, infectious bursal, infectious anaemia and Newcastle. The infectious bronchitis valency can also preferably be added thereto.
On this basis of 3, 4 or 5 valencies, it will be possible to add one or more of the avian plague, laryngotracheitis, pneumovirosis and encephalomyelitis valencies.
As regards the Marek valency, two genes may be used encoding gB and gD, in different plasmids or in one and the same plasmid. The use of the gB gene alone is however preferred.
For the Newcastle valency, the two HN and F chains, integrated into two different plasmids or into one and the same plasmid, are preferably used.
For the infectious bronchitis valency, the use of the S gene is preferred. Optionally, but less preferably, S and M can be associated in a single plasmid or in different plasmids.
For the infectious anaemia valency, the two C and NS1 genes are preferably associated in the same plasmid.
For the infectious laryngotracheitis valency, the use of the gB gene alone is preferred. Optionally, but less preferably, the two gB and gD genes can be associated in different plasmids or in one and the same plasmid.
For the pneumovirosis valency, the use of the two F and G genes, in a single plasmid or in different plasmids, is preferred For the avian plague valency, the use of the HA gene is preferred. Optionally, but less preferably, it is possible to use the associations HA and NP or HA and N in different plasmids or in one and the same plasmid. Preferably, the HA sequences from more than one influenza virus strain, in particular from the different strains found in the field, are preferably associated in the same vaccine. On the other hand, NP provides cross-protection and the sequence from a single virus strain will therefore be satisfactory.
For the encephalomyelitis valency, the use of env is preferred.
The vaccine formula according to the invention can be presented in a dose volume of between 0.1 and 1 ml and in particular between 0.3 and 0.5 ml.
The dose will be generally between 10 ng and 1 mg, preferably between 100 ng and 800 xcexcg and preferably between 0.1 xcexcg and 50 xcexcg per plasmid type.
Use will be preferably made of naked plasmids, simply placed in the vaccination vehicle which will be in general physiological saline and the like. It is of course possible to use all the polynucleotide vaccine forms described in the prior art and in particular formulated in liposomes.
Each plasmid comprises a promoter capable of ensuring the expression of the gene inserted, under its control, into the host cells. This will be in general a strong eukaryotic promoter and in particular a cytomegalovirus early CMV-IE promoter of human or murine origin, or optionally of another origin such as rats, pigs and guinea pigs.
More generally, the promoter may be either of viral origin or of cellular origin. As viral promoter other than CMV-IE, there may be mentioned the SV40 virus early or late promoter or the Rous sarcoma virus LTR promoter. It may also be a promoter from the virus from which the gene is derived, for example the gene""s own promoter.
As cellular promoter, there may be mentioned the promoter of a cytoskeleton gene, such as, for example, the desmin promoter (Bolmont et al., Journal of Submicroscopic Cytology and Pathology, 1990, 22, 117-122; and Zhenlin et al., Gene, 1989, 78, 243-254), or alternatively the actin promoter.
When several genes are present in the same plasmid, these may be presented in the same transcription unit or in two different units.
The combination of the different vaccine valencies according to the invention may be preferably achieved by mixing the polynucleotide plasmids expressing the antigen(s) of each valency, but it is also possible to envisage causing antigens of several valencies to be expressed by the same plasmid.
The subject of the invention is also monovalent vaccine formulae comprising one or more plasmids encoding one or more genes from one of the viruses above, the genes being those described above. Besides their monovalent character, these formulae may possess the characteristics stated above as regards the choice of the genes, their combinations, the composition of the plasmids, the dose volumes, the doses and the like.
The monovalent vaccine formulae may also be used (i) for the preparation of a polyvalent vaccine formula as described above, (ii) individually against the actual pathology, (iii) associated with a vaccine of another type (live or inactivated whole, recombinant, subunit) against another pathology, or (iv) as booster for a vaccine as described below.
The subject of the present invention is in fact also the use of one or more plasmids according to the invention for the manufacture of an avian vaccine intended to vaccinate animals first vaccinated by means of a first conventional vaccine (monovalent or multivalent) of the type in the prior art, in particular selected from the group consisting of a live whole vaccine, an inactivated whole vaccine, a subunit vaccine, a recombinant vaccine, this first vaccine having (that is to say containing or capable of expressing) the antigen(s) encoded by the plasmids or antigen(s) providing cross-protection.
Remarkably, the polynucleotide vaccine has a potent booster effect which results in an amplification of the immune response and the acquisition of a long-lasting immunity.
In general, the first-vaccination vaccines can be selected from commercial vaccines available from various veterinary vaccine producers.
The subject of the invention is also a vaccination kit grouping together a vaccine formula according to the invention and a first-vaccination vaccine as described above. It also relates to a vaccine formula according to the invention accompanied by a leaflet indicating the use of this formula as a booster for a first vaccination as described above.
The subject of the present invention is also a method of avian vaccination, comprising the administration of an effective vaccine formula as described above. This vaccination method comprises the administration of one or more doses of the vaccine formula, it being possible for these doses to be administered in succession over a short period of time and/or in succession at widely spaced intervals.
The vaccine formulae according to the invention can be administered in the context of this method of vaccination, by the different routes of administration proposed in the prior art for polynucleotide vaccination and by means of known techniques of administration.
The intramuscular route, the in ovo route, the intraocular route, nebulization and drinking water will be targeted in particular.
The efficiency of presentation of the antigens to the immune system varies according to the tissues. In particular, the mucous membranes of the respiratory tree serve as barrier to the entry of pathogens and are associated with lymphoid tissues which support local immunity. In addition, the administration of a vaccine by contact with the mucous membranes, in particular the buccal mucous membrane, the pharyngeal mucous membrane and the mucous membrane of the bronchial region, is certainly of interest for mass vaccination.
Consequently, the mucosal routes of administration form part of a preferred mode of administration for the invention, using in particular neubilization or spray or drinking water. It will be possible to apply the vaccine formulae and the vaccination methods according to the invention in this context.
The subject of the invention is also the method of vaccination consisting in making a first vaccination as described above and a booster with a vaccine formula according to the invention.
In a preferred embodiment of the process according to the invention, there is administered in a first instance, to the animal, an effective dose of the vaccine of the conventional, especially inactivated, live, attenuated or recombinant, type, or alternatively a subunit vaccine so as to provide a first vaccination, and, after a period preferably of 2 to 6 weeks, the polyvalent or monovalent vaccine according to the invention is administered.
The invention also relates to the method of preparing the vaccine formulae, namely the preparation of the valencies and mixtures thereof, as evident from this description.